1. Field of the Invention
This disclosure relates generally to filters for vacuum cleaners, and more particularly to replaceable filters for vacuum cleaners, as well as vacuum appliance systems incorporating and using such filters.
2. Description of the Related Art
Vacuum appliances, in particular vacuum cleaners and wet/dry vacuum cleaners, whether they be strictly relegated to cleaning up dry materials, or if they are capable of both wet and dry clean up, require some method to separate the dust and the dirt from the air that is exhausted back into the surroundings during operation. Typically, vacuum filters are used in order to prevent debris from re-entering the area being cleaned. Hence, filters are commonly used to perform these separation functions. Associated with the use of such filters is often a need to remove and re-attach the filter from the vacuum appliance, for example, when cleaning the filter or replacing an old or damaged filter with a new filter. Further, with regard to vacuum cleaners of the type known as “wet/dry” vacuum cleaners, the filter is often also removed when the vacuum cleaner is suctioning liquids. Consequently, special structures often accompany a typical wet/dry vacuum cleaner in order to accommodate removing and replacing the filter.
With regard to the operation of a vacuum appliance or related air-moving system, it is typical that a suction system with a motor creates the vacuum and is mounted in a lid that is removably attached to a collection drum for receiving the vacuumed materials. A portion of the lid, herein termed a mounting assembly, extends at least partially downward into the drum and mounts a filter support assembly, commonly referred to as a “filter cage”, that generally covers a vacuum intake to the suction assembly in the lid. The cage can be made of plastic such as polypropylene, may be generally a cylindrically-shaped molded or extruded part having a series of axial and circumferential support ribs with a large percentage of open surface area to support the filter extended around the cage, and acts (at least in part) to prevent the unwanted radially inward collapse of the filter during vacuum operation. The axial ribs typically align with a longitudinal axis through the cage and the circumferential ribs are often at substantially right angles to the axial ribs. This type of cage construction creates a relatively stiff component in the axial direction. In addition to supporting the filter, the cage can provide a safety shield from user access to the impeller, and may further optionally contain a float or similar device that protects the vacuum cleaner from water being inadvertently suctioned into the impeller.
The vacuum system inside the lid of the vacuum typically suctions external dirty air or water through a hose into an opening in the drum or lid so that the dirt or water is deposited into the drum. Remaining material, mainly air, then flows radially inward through the filter for removal of dirt and debris and continues through the cage into a suction impeller in the lid, and then is exhausted from the vacuum cleaner.
The filter is commonly attached to the mounting assembly by a threaded stud, or “cage stem”, and nut combination on the end of the cage, which acts to place the filter in axial compression, utilizing the longitudinal stiffness of the axial ribs. In typical use, the filter is inserted over the cage, and a mounting flange of rigid material, such as plastic, is attached to the cage or mounting assembly and used to compress or “sandwich” the filter between the flange and the mounting assembly. The compressive, mechanical force on the entire filter body and its filter element is the primary force used to seal the filter to the vacuum cleaner and prevent unwanted leakage through the vacuum cleaner. Thus, a structurally sound and supportive cage is important to the overall function of the filter and in general the vacuum cleaner. The filter may also be attached in position by some other method, such as clamping one or more seals of the filter directly to the mounting assembly or lid. A structurally rigid cage is again necessary to guard against entry of unwanted objects, or fingers, into the impeller and to house the intake cutoff float.
Experience has shown that while these vacuum filter systems and mechanisms work, they often suffer from being awkward or cumbersome to use, which in turn makes the changing of the filter itself difficult, cumbersome, or time consuming. Further, those vacuum systems wherein the filter is attached to a mounting assembly by way of a threaded stud-and-nut system on the end of the filter cage, using a threaded nut to retain the filter in a state of axial compression, can be time consuming to operate, and the employment of a separate filter nut or similar attachment mechanism is undesirable because such parts can be readily lost or misplaced during the course of filter replacements. Additionally, some of the more complex filter system designs employ mechanisms that add unnecessary cost to the overall vacuum appliance product. Finally, those filter system designs that do not use or require filter retaining mechanisms can often result in the filter becoming readily dislodged and/or the seal of the filter to the vacuum is broken when the vacuum is dropped or jarred, which in turn can damage both the filter itself, and cause unwanted leakage of liquid or debris into the vacuum system and motor.
This application for patent discloses filter assemblies for use with vacuum appliances, such as wet/dry vacuum cleaners, which eliminates the need for any separate retaining mechanism to install the filter to the vacuum appliance, allows the filter to be replaced and/or cleaned quickly and effectively, readily seals to the mounting assembly of the vacuum appliance, remains secure during normal operation without unwanted dislodgment from the jarring and rough handling of the vacuum appliance, and which is readily retro-fit to existing vacuum appliance units already in the marketplace, negating the consumer from having to purchase a new vacuum appliance, such as a new wet/dry vacuum, in order to use the filter assemblies of the present disclosure.